1. Field of the Invention
This invention relates in general to load bearing supports and more particularly to an adjustable support for a mobile home.
2. Description of the Related Art
A mobile home typically includes a bottom framework of I-beams or channel beams. When the mobile home is parked for occupancy, these beams are rigidly supported so as to prevent any movement. One common support means, a top screw support, denoted generally as 10, is shown in FIG. 1. Top screw support 10 generally includes a stand 11 and an adjustable support head 15. Stand 11 includes a base 12 from which legs 13 extend in a pyramid shape to support at their apex a bearing 14 having a central bore (not seen). Support head 15 includes a threaded screw 16 which passes thru the central bore of bearing 14. Nut 18 is threaded on screw 16 and bears against bearing 14 such that turning nut 18 raises and lowers screw 16. A load support plate 17 on the upper end of screw 16 is placed under a frame beam. Typically, a plurality of top screw supports 10 would be placed under frame beams to support a mobile home.
Top screw supports 10 have a major problem; they tend to fail when subjected to lateral loads such as experienced during an earthquake. During an earthquake, load support plate 17 receives large lateral forces in additional to the standard compressive load forces. These lateral forces exert a shear force and a large moment force on screw 16 near nut 18 and bearing 14 which leads to failure by bending. Screw 16, has only a small cross-sectional moment of inertia to resist shear and bending forces and is additionally weakened by its threads, which are stress raisers. Support failure may lead to severe damage to the mobile home and injury to its occupants.
Also, it should be noted that with top screw support 10, legs 13 carry both the load forces (compressive) and the moment forces (compressive on one side and tensile on the other). These combined forces cause some prior art top screw supports to fail during earthquakes because of leg failure by buckling.
On prior art supports, load support plate 17 has a flat or nearly flat upper surface for placing under a frame beam. Consequently, during large lateral movement by the mobile home such as because of an earthquake of toronado, the beam may simply slide off the support plate.
Therefore, it is desirable to have an adjustable load bearing support for a mobile home that is much more capable of withstanding lateral loading than prior art supports.
It is additionally desirable that such an improved support should positively attach to the frame beams to prevent disengagement during lateral movement.